Strap fitting plate



Feb. 20, 1940. F. R. uTLER El AL STRAP FITTING PLATE Filed July 14, 1937 Y 1 VENTOR H250 E3 072,518 4 0924. E PETEES of fitting lens straps to lenses whereby the oper- Patented Feb. 20, 1940 UNITED STATES.

antics PATENT lorries STRAP FITTING PLATE Fred R. Cutler, Kansas City, Mo., and Carl 3..

Peters, Salina, Kana, assignors to American Optical Company, Southbridge, Mass, a voluntary association of Massachusetts i Application July 14, 1937, Serial No 153,600

2 Claims. (o1. 33 200) Another object of the invention is to provide lo new and improved means and method of fitting lens straps to lenses, whereby the straps may be bent over a member whose thickness is less than the lens thickness, to allow for the after- III-III of Fig. I; and Fig. IV is a fragmentary sectional View showing workingorsetting ofthe strap material.

Another object isto providemeansand method hers and strap formingand fitting members in designated inter-relation.

Another object is to provide means for fitting 36 lens straps to lenses, whereby the gauging memher is provided with means for attaching it to a .fixed holder.

Another object is to provide means for fitting lens straps to lenses having a body portion which gklis tapered to provide a peripheral edge having a varying thicknessthroughoutthe contour of the body portion and having a series of openings located at varying selected points on said body portion, said openings being so positioned and g ldirected with respect to the dimensional characteristics of said body portion as to effectively simulate the position of the strap attaching holes of, a lens in accordance with a standard set up in the common practice of the art.

45" Still another object of the invention is to pro-- vide, new, and improved means for fitting lens straps to lenses whereby the gauging member is providedwit'h means for sizing and for obtaining an effective trial fit of the strap on the lens.

to Other objects and advantages ofthe inven tion will become apparent from the following description taken in connection with the accompanying drawing, and it will be apparent that many changes may be made in thedetails of construction, arrangementof parts and methods shown and described, without departing from the spirit of the invention as expressed in the ac;

conipanying claims. We, therefore, do not wish. to be limited to exact details of construction, ar-

rangement of parts and method shown and d8, 5"

scribed, as the preferred form only has been given by the way of illustration.

Referring to the drawing: Fig. I is a plan view of the concave sideof the gauging device embodying the invention; 0

Fig, II is a sectional view taken on line II- -II of Fig. I; i

. Fig. III is a sectional View taken on line a lens strap attached to a lens.

The fitting of lens straps to lenses has been a very difficult and delicate procedure, calling for. the services of highly skilled and experienced" operators. In order to provide an aperture be tween the strap ears which will properly contain the lens, the ears must be bent beyond the point at which the aperture is equal to the lens thickness, toa pointfrom whichthe after-working,

of the metal will spring the ears apart enough 2 so that the aperture provided by the final set of the metal will be equal to, or a trifle less than,

the thickness of the lens. The trial and error method used in the past has been far from satisfactory, because it was not only diliicult but inaccurate. The strap may have a seemingly good fit at the time of assembly, but actually the fitting may be too tight, and thus cause a strain in the lens which may lead to its breakage or may be too lose and fail to properly support the lens. In the case of curved or meniscus lenses, thediificulty was even more pronounced due to the angle at which the ears of the straps must be placed to follow the contour of the surface of the lens. In the pro- 40 cedureof fitting lens straps, the operation of gauging the lens thickness and that of bending the strap ears to produce the desired aperture between the ears has in most instances in the past been distinctly separate, and there has been. no known single device having definite means for determining the amount of aperture between the ears of the strap and also having means correlated with the first means to properly provide the strap with said aperture.

Referring to the drawing, the present invention allows for many advantages over the usual method. It provides a gauge plate which has a body portion ll], circular in design, cupped, as

shown in Figs. II and III, to form meniscus conear apertures with the gauge hole.

tours with approximately a 6.00 base curve, and having substantially a curved wedge on prism taper shape. Obviously the curve may be other than a 6.00 base but this is selected because it covers the greatest range of lens shapes now in use. The body portion lll has a central opening H and a threaded portion l2 in said opening whereby the gauge plates may be screwed to a holder to facilitate its handling. The gauge plate may be used without a holder if so desired.

On one side of the body portion Ill, as shown in in Fig. II the strap ears are first placed over the plate adjacent one of the said gauge. holes as in position is. over the body portion in, as shown at is. An aligning tool ll is then used to line up the strap This posh tioning and lining up provides an effective trial fit of the strap as Whenin position on the lens. Difierent curves of lenses require slightly differ-' ent positions of the strap ear attachment pen ing with respect to the length of said car. This position is determined by the above mentioned trial fit and is arrived at by so bending the strap j ear as to adjust it the amount required to bring the strap and plate apertures into alignment. I

Each of said gauge holes ill-is definitely .re-- lated to one of the gauge slots it the nations indicated at Eli and 2t so that the proper hole which is to be used determined by the of the art.

gauge slot in which the edge of the lens fits during the thickness gauging operation.

The gauge holes iii are positioned on through the gauge plate iii in a very defii.

relation to thebposition cl strap attaching hol i on and through lenses in the common prac ce That is, each of said gauge holes positioned at a distance from the peripheral of the body portion lii equal to that which is commonly set up as a standard between the edgeand the strap attached hole of a lens. Also,'as illustrated in Fig. 11, and in keeping with the common practice in drilling lens strap-connecting holes in lenses, the opening I is so formed that its longitudinal axis 22 is normal toa line tangent with the surface of the plate at the location at which the said opening is formed in said plate.

The axis 22 then is at an angle with the plane of the plate periphery as indicated by line 23, said angle being substantially equal to a similar angle between the corresponding-axis and plane of a lens to which the lens strap is to be attached.

Ophthalmic lenses of today are commonly of meniscus shape and it is common practice in the rimless lens art to maintain the edge thickness as thin as is practical. However, in order to meet difierent prescriptive requirements, this edge thickness varies. This is one reason Why this invention is important, since it provides the means whereby an accurate and positive adjust- 'ing and sizing of the strap and aligning of the connecting openings may be obtained. so that the strap may be accurately fitted on a lens: of a particular thickness and shape with the standard placement of strap attaching hole.

It is usual in the art of edging ophthalmic Then the ears are pressed together lenses to so form the peripheral edge of the lens that itsv intersection with any plane containing the line which'is the physical axis of the lens after cutting, will be parallel with said axis,

Each slot E3 is numbered, as at 29, and has a hole liiwhich iscorrespondingly numbered, as at 26, and these holes #5 are so constructed and arranged adjacent the peripheral edge of the gauge plate that the taper at each location will provide the desired thickness for the forming of a strap to fit a lens of a thicknessestablished by the corresponding gauge slot.

The thickness of the gauge plate id at any of the holes M is a little less than the width of the correspondingly numbered slots. This is made possible by the curved wedge or prism taper shape which is designed with a view to providing a plurality of plate thicknesses. The amount of the difference between the above mentioned thickness and width is determined by the afterworking factor of the material used in the strap, and must be carefully calculated and taken into consideration in the designing of the gauge plate.

The strap it is then positioned and assembled with a lens it as illustrated in Fig. IV.

Thus it may be seen that the trial and error method of fitting lens straps to lenses has been discarded, and an easy and accurate method provided whereby the lens is first gauged for thickness, the strap then positioned over the gauge plate at the proper hole for forming for an effective trial fit, and then positioned on and assembled to a lens.

The strap ears l9 and 28 are bent over the gauge plate, making the aperture between them of a distance slightly less than that of the width of the corresponding slot, enough so that the afterworking of themetal in the straps will spring i a lens of the thickness indicated by the gauge slot used. At the same time, when the strap ears are the ears apart just enough ton-lake a good fit on bent over *the meniscus shaped gauge plate, they 7 are formed to an angle and curvewhich will-permit the strap to be readily attached to the lens. The relation between the slots and holes in the gauge plate makes possible the obtaining of a quick and accurate fit of the strap ears to the lens surfaces, and obviates the danger of loose fitting parts or strain and cracking of lenses.

Frointhe foregoing description it will be seen that a particular advantage of this invention is,

1. A gauge member for gauging and fitting a lens strap to alens prior to assembly, comprising a body portion cupped to a controlled curvature simulating a standard base curvature of a com mercial ophthalmic lens, and having a continuous curved contour edge portion which is tapered to provide varying thicknesses along said edge portion, with the thickness of the said body portion,

at designated locations being of a controlled amount less than the edge thickness of a commercial ophthalmic lens of a standard type to which the lens strap is to be fitted, whereby portions of the lens strap overlying the side surfaces of the gauge member may be pressed until the distance between said lens strap portions isless than the edge thickness of the lens, by an amount such that upon release of said pressure, the said strap portions will inherently separate until the distance between them is substantially equal to the edge thickness of the lens to which said strap is to be attached and the said overlying portions will be shaped to the cupped curvature of said gauge member and similarly substantially to the cupped curvature of the lens.

2. A gauge member, for gauging and fitting a lens strap having perforated strap ears to a lens having an attaching opening therein prior to assembly, comprising a body portion cupped to a controlled curvature simulating a standard base curve of a commercial ophthalmic lens, and having a continuous curved contour edge portion which is tapered to provide varying thicknesses along said edge portion, said body portion having a plurality of openings therein of substantially the same size and spaced inwardly of its contour edge amounts similar to the distance of the perforation in the lens from the adjacent edge of l i said lens with the thickness of said body portion at the location of each of said openings being less than the edge thickness of a commercial ophthalmic lens to which the lens strap is to be fitted by an amount sufiicient to compensate for thetendency of said material of the strap ears to spring outwardly after being fitted and pressed over the opposed sides of said body portion at a location on said body portion selected according to the particular edge thickness of the lens to which the strap is to be fitted so that after said outward springin the space between the strap will be substantially equal to that. of the thicimess of the lens with the adjacent opening in said gauge plate providing means for aligning the openings in the strap ears with the strapv fitted to said plate prior to securing the lens strap to the lens.

- FRED R. CUTLER, CARL R. PETERS. 

